/** 
 *  Copyright 2010 Matthew Werny & Burk Price.
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *       http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *  under the License.
 */
package net.iceflow.db.migration.version.extractor;

import net.iceflow.db.migration.version.VersionExtractor;
import net.iceflow.db.migration.exception.MigrationException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Assumes the filename, minus the extension, is the migration version.
 * <p/>
 * Examples:
 * <ul>
 * <li>20080518134512_create_foo.sql -> 20080518134512</li>
 * <li>20080718214051_add_foo_name.sql -> 20080718214051</li>
 * <li>012_create_bar.sql -> 012</li>
 * </ul>
 */
public class SimpleVersionExtractor implements VersionExtractor {

	private static final Pattern FILENAME_PATTERN = Pattern.compile("^(\\d+).*");

	public String extractVersion(String name) {
		try {
			Matcher matcher = FILENAME_PATTERN.matcher(name);
			matcher.find();
			return matcher.group(1);
		} catch (Exception e) {
			throw new MigrationException("Error parsing migration version from " + name, e);
		}
	}
}
